Method for the Operation of a Filter Press Comprising a Plunger

ABSTRACT

A method of operating a filter press for solid-liquid separation of a product, the filter press comprising a press jacket with an end, and a ram in the press jacket and movable relative to the end to define a pressing space. The method comprising loading a product to be pressed in the pressing space; positioning the ram in a start position so that the product only partially fills the pressing space; advancing the ram, during a first phase of a forward movement, from the start position to a full contact position where the volume of the pressing space becomes equal to a volume of the product; and advancing the ram toward the end from the full contact position during a second phase of the forward movement, the ram exerting no pressure on the product during the first phase but exerting pressure on the product during the second phase to press liquid phase out of the product. At the full contact position, the ram is advanced at a forward velocity lower than an average forward velocity over the first phase.

TECHNICAL FIELD

The invention pertains to a method for operating a filter press for thesolid-liquid separation of a product with a pressing space containing aram, to an application of the method, to a filter press for implementingthe method, and to an application of the filter press according to theintroductory clauses of the independent claims.

PRIOR ART

Filter presses with a ram are used especially in the food industry,e.g., in the production of fruit juices. The ground-up fruit pulp isintroduced into the pressing space and then subjected to pressure by theforward movement of the ram. The liquid phase is conducted away throughfilter drainage elements, and the solid phase remains behind in thepressing space. Because, for reasons of process technology, theavailable pressing space is not completely filled with pulp, the rammoves forward during a first phase without actually exerting anypressure on the pulp; the volume of the pressing space is simply reduceduntil it matches the quantity of pulp present in the pressing space.After the volume of the pressing space has become equal to the volume ofthe pulp, the ram executes the second phase of its forward movement, inwhich it exerts pressure on the pulp to squeeze liquid phase out of it.During the first phase of the forward movement, only weak feed forcesare necessary, but at the same time it is desirable to use the highestpossible forward velocity. During the second phase, conversely, strongfeed forces are necessary at a relatively low forward velocity. For thisreason, hydraulic cylinders and hydraulic pumps which can switch fromone setting to another are used almost exclusively today to drive theram. Thus a high volume flow rate of hydraulic fluid can be supplied tothe hydraulic cylinder at low pressure during the first phase of theforward movement, and a low volume flow rate can be supplied at highpressure during the second phase. The switchover is easily accomplishedby increasing the pressure in the hydraulic circuit when the ram makesfull contact with the pulp filling the pressing space. The existingmethod, however, does not allow for any further increase in the forwardvelocity, even though this would be advisable from an economicstandpoint. The velocity is not increased, however, because, if it were,the resulting increase in the pressure peak in the pressing space whichoccurs when the ram makes full contact with the pulp would interferewith the formation of a desirable secondary filtering layer on thefilter drainage elements, and thus an increased amount of suspendedsolids would be introduced into the squeezed-out liquid phase.

DESCRIPTION OF THE INVENTION

The problem is therefore to make available a method for operating afilter press and a filter press which do not suffer from thedisadvantages of the state of the art or which at least minimize thesedisadvantages.

This problem is solved by the method and by the filter press accordingto the independent claims.

A first aspect of the invention pertains to a method for operating afilter press with a pressing space and a ram for the solid-liquidseparation of a preferably organic, liquid-to-pasty product. In a firststep of the method, the filter press is prepared by loading the productto be subjected to solid-liquid separation into the pressing space andby moving the ram back to a rear position. In this situation, the volumeof the quantity of product present in the pressing space is considerablysmaller than the volume of the pressing space. In this first step of themethod, the pressing space is therefore only partially filled withproduct; the degree to which the space is filled in this operatingsituation is therefore less than 1. In the following second step, theram is moved forward from the rear position, thus reducing the volume ofthe pressing space, until it makes full contact with the product presentin the pressing space. This full contact occurs when the volume of thepressing space has become equal to the volume of the product in thepressing space. In this first phase of its forward movement, the ramexerts essentially no pressure on the product. When the ram is now movedforward during the second phase, after the volume of the pressing spacehas become equal to the volume of the product in the pressing space, itwill thus exert pressure on the product and squeeze liquid phase out ofit. At the moment when the volume of the pressing space and the volumeof the product in the pressing space become equal, i.e., at the momentwhen the ram makes full contact with the product at the end of the firstphase, the ram is advanced at a forward velocity which is lower than theaverage forward velocity averaged over the first phase of its forwardmovement. Over most of the first phase of the forward movement of theram, during which the ram exerts essentially no pressure on the productin the pressing space, the ram travels much faster than it does at theend of this phase and/or at the beginning of the following, second phaseof the forward movement, during which the pressure begins to build up inthe pressing space. As a result, the ram contacts the product at avelocity which is lower than the average forward velocity of the firstphase, and thus the pressure in the pressing space increases gradually,without any pronounced peak, which is desirable.

Through the inventive operating method with a forward velocity in thefirst phase of ram movement which is much higher than that according tothe state of the art, it is possible to achieve higher processingoutputs without increasing the amount of suspended solids in thesqueezed-out liquid phase. Thus a qualitatively equivalent product canbe obtained at lower cost.

In a preferred exemplary embodiment of the method, the forward velocityof the ram during the first phase of its forward movement is decreasedin stages or continuously from a maximum forward velocity to the forwardvelocity present when the ram makes full contact with the product. Thisreduction in velocity is preferably carried out in accordance with apredetermined forward velocity profile, which can be fixed orpredetermined as a function of certain process parameters such as theamount of product actually in the pressing space and/or on theproperties of the product. In the case of presses with a ram which isadvanced in a horizontal plane, it is also provided that the forwardvelocity during the first phase of forward movement until the ram makesfull contact with the product is controlled as a function of therequired forward-feed force in such a way that the forward velocity isdecreased as the forward-feed force increases as a result of thecompression of the product in the pressing space. As a result, it easyto realize a self-regulating action during the first phase of theforward movement.

The ram is preferably advanced initially from the rear starting positionat a first forward velocity to a predetermined first position in whichthe pressing space is still only partially filled with product and inwhich the ram therefore is not yet in full contact with the product.Starting from this first position, the ram is then advanced at a secondforward velocity to a second position, at which the volume of thepressing space is equal to that of the product in the pressing space andthe ram begins to exert pressure on the product in the pressing space.The second forward velocity is lower than the first forward velocity. Asa result, the ram, during its forward movement between the first and thesecond position, contacts the product at the lower second velocity andthen starts to exert pressure on it, with the result that liquid phasebegins to be squeezed out of the product. This method offers theadvantage that it can be realized with low-cost switchable hydraulicdrives for the ram and is therefore also suitable for the operation ofalready existing filter presses.

It is also preferable for the first position to be predetermined in sucha way that, when it is reached, the pressing space is filled to aspecific degree or that the ram is a specific distance away from theposition in which the volume of the pressing space and the volume of theproduct in the pressing space are equal, i.e., the position in which theram therefore makes full contact with the product. As a result, it ispossible to switch to the lower second forward velocity just before theram makes full contact with the product, so that minimal ram traveltimes are obtained and it is ensured simultaneously that the ram makesfull contact with the product at the lower second forward velocity.

It is also preferable for the ram to be advanced during the second phaseof the forward movement at the second forward velocity until apredetermined pressure is reached in the pressing space. As a result, itis possible to achieve an almost seamless transition between the initialphase and the actual squeezing process.

In another preferred embodiment of the method, before the ram isadvanced, the ram is used to perform a preceding pressing cycle in whichliquid phase is squeezed from the product. So that the forward velocityprofile—and, in the case of graduated velocity profiles, the firstposition—can be predetermined, the position of the ram at the end of thepreviously completed pressing operation is determined. On the basis ofthis determined position and additional knowledge concerning the amountof product, wash-out liquid, or liquid product phase which may have beenadded or removed after the end of the preceding pressing cycle, it isthen possible to establish in advance the probable position which theram will assume when it makes full contact with the product present inthe pressing space and to adapt the forward velocity profilecorrespondingly. This makes the method especially suitable for pulsedfilling operations with intermediate squeezing-out of liquid phase orfor interval-wise pressing with intermediate loosening of the productand possibly the additional introduction of washing fluid to thepressing space. In addition to establishing the position of the ram atthe end of the previously completed pressing cycle, it is also possibleto determine the pressure in the pressing space at the time when the ramreaches this position and to use this recorded pressure value as well toestablish the probable position of the ram when it makes full contactwith the product in the pressing space or to adjust the forward velocityprofile so that changes in the compressibility of the pulp, for example,can be taken into account.

It is preferred accordingly to supply additional product or wash fluidto the pressing space during the time between the end of the precedingpressing cycle and the moment at which the volume of the pressing spaceand the volume of the product in the pressing space become equal, i.e.,when the method is therefore being used in conjunction with pulsedfilling mode or wash-out mode. Here the advantages of the inventivemethod become especially obvious.

It is also preferable to determine the quantity of product or wash fluidsupplied to the pressing space as a basis for predetermining theassociated forward velocity profile and also, in the case of a graduatedvelocity profile, as a basis for predetermining the first position, sothat each individual pressing operation can be optimized.

In yet another preferred embodiment of the method, the forward velocityof the ram during the second phase of its forward movement is regulatedin such a way that a certain pressure curve is followed while liquidphase is being squeezed out in the pressing space as soon as a certainpressure is reached in the pressing space or as soon as the ram reachesa certain position.

It is advantageous in this case to select a pressure curve specificallyfor the product to be pressed and/or as a function of the actual runoffof liquid phase, because it is thus possible to achieve optimal pressingresults.

In yet another preferred embodiment of the method, the method isimplemented with a filter press in which a plurality of flexible filterdrainage elements is installed between the ram and the other boundariesof the pressing space to allow the liquid phase of the product to leavethe pressing space during the pressing cycle while simultaneouslyholding back the solid phase in the pressing space. Such presses areespecially suitable for operation according to the inventive method.

A second aspect of the invention pertains to an application of themethod according to the first aspect of the invention to thesolid-liquid separation of fruit or vegetable pulps. In thisapplication, the advantages of the invention become especially evident.

A third aspect of the invention pertains to a filter press with apressing space for holding a product to be pressed, with a ram in thepressing space for exerting pressure on the product, and with a presscontrol unit, which makes it possible to operate the press, preferablyautomatically, according to the method covered under the first aspect ofthe invention.

In a preferred embodiment of the filter press, the press control unit isable to control the forward movement of the ram, which starts from arear position in a pressing space not completely filled with product, insuch a way that the ram, starting from the rear position, moves forwardin a first phase during which it does not exert any pressure on theproduct but does decrease the volume of the pressing space until it isequal to the volume of the product in the pressing space and then, in asecond phase of its forward movement, exerts pressure on the product tosqueeze liquid phase from it, where, at the time that the volume of thepressing space becomes equal to the volume of the product in thepressing space, the ram has a forward velocity which is lower than theaverage forward velocity averaged over the first phase of its forwardmovement. This can be accomplished by implementing certain fixed orvariable, continuous or graduated forward velocity profiles. The drivesused for continuous forward velocity profiles are preferably hydraulicdrives with continuously variable axial piston pumps, although pumpswith bypass valves which can switch from one output setting to anothercan also be used.

It is preferable for the press control unit to have the ability tocontrol the forward velocity profile as a function of certain processparameters, preferably as a function of the quantity of product presentin the pressing space and/or on the type of product, so that an optimalforward velocity profile can be implemented for each pressing cycle.

The press control unit preferably has the ability to control the forwardmovement of the ram in such a way that the ram, starting from the rearposition, moves initially at a first forward velocity to a predeterminedfirst position, in which the pressing space is still only partiallyfilled with product, and then, starting from this first position, movesat a second forward velocity which is lower than the first forwardvelocity to a second position, in which the product present in thepressing space is subjected to pressure by the ram and liquid phase issqueezed from the product. Filter presses of this type can be realizedwith low-cost switchable hydraulic drives and can also be realized bymodifying existing filter presses by adding a suitable press controlunit.

If the press control unit is able to determine in advance the degree towhich the pressing space is filled at various positions of the ramand/or to determine the probable position of the ram when the volume ofthe pressing space becomes equal to the volume of the product in thepressing space, preferably during the forward movement of the ram withinthe cycle in question, and to configure the forward velocity profile insuch a way that the first position is reached a certain distance awayfrom the position of the ram at which the volume of the pressing spaceis equal to the volume of the product in the pressing space, then it ispossible to determine the first position, i.e., the point at which theforward velocity is switched to the lower velocity, just before the rammakes full contact with the product and thus to optimize the output ofthe press.

It is also advantageous for the press control unit to have the ability,in the second phase of the forward movement, to control the forwardmovement in such a way that a pressure curve, preferably predeterminedas a function of the product to be pressed and/or a pressure curvecalculated as a function of the actual juice runoff, can be implementedin the pressing space during the squeezing-out of liquid phase from theproduct, so that here, too, individual optimization is possible.

In yet another preferred embodiment of the filter press, the presscontrol unit also has the ability to control the supply of product to besqueezed and/or the supply of wash fluid to the pressing space,preferably in an automatic manner, so that the entire operation of thepress, starting with the filling step and continuing all the way to theemptying step, can be completely automated.

In still another preferred embodiment, the filter press is built in sucha way that it has a plurality of flexible filter drainage elementsinstalled between the ram and the other boundaries of the pressing spaceto allow the liquid phase of the product to leave the pressing spacewhile simultaneously holding back the solid phase of the product in thepressing space during the pressing cycle. Such presses make it possibleto obtain especially high yields, and their output can be increased evenmore by the use of the invention.

A fourth and last aspect of the invention pertains to the use of thefilter press according to the third aspect of the invention for thesolid-liquid separation of fruit or vegetable pulps in the foodindustry. An especially high degree of economic benefit can be obtainedhere because of the large quantities which are processed.

SHORT DESCRIPTION OF THE DRAWINGS

Additional embodiments, advantages, and applications of the inventioncan be derived from the dependent claims and from the followingdescription of the figures:

FIG. 1 shows a cross section through a horizontal ram filter press forimplementing the inventive method;

FIG. 2 shows a diagram of the change in the stroke H of the ram and inthe pressure P in the pressing space versus the time t during the use ofa first inventive method for operating the filter press of FIG. 1;

FIG. 3 is a diagram similar to FIG. 2 showing a second inventiveoperating method;

FIG. 4 is a diagram similar to FIG. 2 showing a third inventiveoperating method; and

FIG. 5 is a diagram similar to FIG. 2 showing a fourth inventiveoperating method.

WAYS TO IMPLEMENT THE INVENTION

A horizontal ram filter press for implementing the inventive method isshown in cross section in FIG. 1. The ram filter press 1 comprises acylindrical press jacket 6, in which a ram 4 is installed with freedomof horizontal movement. The jacket is closed off at the end opposite theram end by a pressure plate 7. The press jacket 6, the pressure plate 7,and the ram 4 together form a pressing space 3, which holds the material2 to be pressed, the volume of which space can be changed by moving theram 4. Installed between the pressure plate 7 and the ram 4 is aplurality of flexible filter drainage elements 5, which, during thepressing cycle, carry the liquid phase of the material 2 into collectingchambers 8, 9 in the pressure plate 7 and in the ram 4 and from there torunoff lines 10, 11. At the same time, the drainage elements hold backthe solid phase in the pressing space 3. The material 2 to be pressed isfed to the pressing space 3 through a central filling opening 12, which,after the material 2 has been introduced, is closed off by a slide 13.The ram 4 is driven by a double-acting hydraulic cylinder 14, which isin working connection with a hydraulic pump (not shown) . In thesituation shown here, the ram 4 is located in an appropriate rearposition H1, and the pressing space 3 is approximately half-filled withan appropriate fruit pulp 2 as the product.

When, starting from the illustrated situation, the ram 4 is moved towardthe left in the direction of the pressure plate 7 by appropriateactuation of the hydraulic drive 14, the volume of the pressing space 3is thus progressively reduced. No significant pressure is built up inthe pressing space 3 until the ram 4 makes full contact with the pulp 2at position H2 as a result of the equality now reached between thevolume of the pressing space 3 and the volume of the pulp 2 present inthat space. As the ram continues to move forward, the pressure in thepressing space 3 starts to build up and liquid phase begins to run offfrom the fruit pulp 2 via the filter drainage elements 5 into the runofflines 10, 1.

FIGS. 2-5 show diagrams of the course of the stroke H of the ram (solidline) and of the pressure P in the pressing space (broken line) versusthe time t during the operation of the filter press 1 illustrated inFIG. 1. Several successive pressing cycles separated by phases in whichthe mixed material is loosened (FIGS. 2-4) or separated by phases inwhich more material is added in a pulse-like manner (FIG. 5) are shown.As can be seen, the ram 4, which is in position H4 at the end of thepreceding pressing cycle, is returned at the beginning of the nextpressing cycle to the rear position HI, as a result of which the filterdrainage elements 5 in the pressing space 3 are stretched, the volume ofthe pressing space is simultaneously enlarged, and the pulp 2 in thepressing space 3, the solids content of which has already beenincreased, is loosened. In the method shown in FIG. 5, furthermore, aspreviously mentioned, additional pulp 2 is loaded into the pressingspace 3 as the ram 4 is retracted.

The ram 4 is now moved forward. In all of the methods shown here, thisforward movement begins at the maximum forward velocity and ends at theminimum forward velocity, the various inventive methods shown in FIGS.2-5 differing from each other with respect to the change over time inthis forward movement, i.e., with respect to the forward velocityprofiles.

In the operating method shown in FIG. 2, the entire forward movement ofthe ram 4 starting from the rear, retracted position H1 and continuingto the end of the forward movement, takes place in accordance with acontinuous forward velocity profile, in which the forward velocitydecreases gradually with increasing stroke of the ram. When the ram isin position H2, in which it makes full contact with the pulp 2, it has apredetermined forward velocity V2, which is much slower than the averagefeed velocity V1 m at which it traveled the distance from the rearposition Hi to the full-contact position H2. The continuous forwardvelocity profile is realized by the use of a continuously variable axialpiston pump to supply the hydraulic cylinder 14 and by the appropriateactuation of the pump by a computer-controlled press control unit. Toensure that the ram 4 always has the predetermined second forwardvelocity V2 when it makes full contact with the pulp 2, the end positionH4 of the ram 4 during the previous pressing cycle is determined. Thisend position corresponds essentially to the position H2 which the ram 4will occupy when it makes full contact with the pulp 2 during thefollowing pressing cycle and is used by the press control unit to adjustthe forward velocity profile as appropriate. In this way, the forwardvelocity profile is optimized automatically for each individual pressingcycle.

In the case of the operating method shown in FIG. 3, the forwardmovement of the ram 4 starting from the rear position H1 proceeds at afirst constant forward velocity V1 to a first position H1′, which isjust in front of position H2 at which the ram 4 makes full contact withthe pulp 2. The ram then advances at a second constant forward velocityV2, which is much slower than the first velocity V1, and continues allthe way to a second position H3, which corresponds here to the endposition of the forward movement of the ram. Thus the ram 4 makes fullcontact with the pulp 2 at the slower velocity V2. The graduated forwardvelocity profile is realized here by the use of a two-stage switchinghydraulic pump as the supply unit for the hydraulic cylinder 14 and bythe appropriate switching of the pump at point H1′ by the press controlunit. Here, too, the press control unit determines the end position H4of the ram 4 at the end of the preceding pressing cycle, thusestablishes the position H2 which the ram 4 will occupy when making fullcontact with the pulp 2, and then establishes the switching point H1′ onthe basis of a predefined stroke difference. In this way it can beguaranteed that the switching to the slower forward velocity V2 willalways occur at a certain stroke difference before the point at whichthe ram 4 makes full contact with the pulp 2. In addition to the endposition H4 of the ram, the pressure P in the pressing space reachedwhen the ram arrives in that position can also be determined. Thispressure value can then also be used to help determine the full-contactposition H2 or the switching point H1′, e.g., to take into accountchanges in the compressibility of the pulp over the course of severalsuccessive pressing cycles.

In the case of the operating method shown in FIG. 4, the forwardmovement of the ram 4, as also in the method illustrated in FIG. 3,starting from the rear retracted position H1, proceeds at a first,constant forward velocity V1 to a first position H1′, which is just infront of the full-contact position H2 of the ram 4 with the pulp 2.After that, the ram advances at a second constant forward velocity V2,much slower than the first velocity V1, to a second position H3, whichmeans that the ram 4 makes full contact with the pulp 2 at the slowervelocity V2. In contrast to the method shown in FIG. 3, however, thesecond position H3, which represents the end of the forward movement ofthe ram 4 at the second velocity V2, is not at the end of the entireforward movement of the ram 4 but rather between the position H2 atwhich the ram 4 makes full contact with the pulp 2 and the end of theforward movement. In the present case, the second position H3 is reachedwhen the pressure P in the pressing space exceeds a certain thresholdvalue. When this threshold value is reached, the press control unitswitches to a control variant, in which a predetermined pressure curvein the pressing space is implemented by appropriate control of theforward movement of the ram. Instead of the use of a specific pressurethreshold, it is also possible to use a certain stroke difference withrespect to position H2 as a criterion for the presence of the secondposition H3 and for the subsequent switchover to pressure control mode.

The operating method shown in FIG. 5 differs from that of FIG. 4 only inthat, between the end position H4 of the forward movement of the ram inthe preceding pressing cycle and the full contact of the ram 4 with thepulp 2 in position H2, additional pulp 2 is added to the pressing space3, so that the volume of pulp 2 present in the pressing space 3 isincreased, and the contact position H2 is situated in front of theearlier ram position H4. So that the position in which the ram 4 willmake contact with the pulp 2 and the associated first position H1′ canbe determined, the press control unit in the present case determines notonly the end position H4 of the ram in the preceding pressing cycle butalso the additional quantity of pulp 2 supplied.

Whereas preferred embodiments of the invention are described in thepresent application, it must be pointed out explicitly that theinvention is not limited to these embodiments and that the invention canbe executed in other ways within the scope of the following claims.

1.-23. (canceled)
 24. A method of operating a filter press forsolid-liquid separation of a product, the filter press comprising apress jacket, a press plate at one end of the press jacket, and a ram inthe press jacket and movable relative to the press plate, the pressjacket, the press plate and the ram defining a pressing space having avolume, the method comprising the steps of: preparing the filter pressby loading a product to be pressed in the pressing space and bypositioning the ram in a start position so that the product onlypartially fills the pressing space; advancing the ram, during a firstphase of a forward movement of the ram, from the start position to afull contact position which is positioned between the start position andthe press plate, wherein the volume of the pressing space becomes equalto a volume of the product in the pressing space at the full contactposition, the ram exerting no pressure on the product during the firstphase of the forward movement to press liquid phrase out of the product;and advancing the ram, during a second phase of the forward movement,toward the press plate from the full contact position, the ram exertingpressure on the product during the second phase of the forward movementto press liquid phase out of the product, wherein at the full contactposition, the ram is advanced at a full contact forward velocity whichis lower than an average forward velocity averaged over the first phaseof the forward movement.
 25. The method of claim 24, wherein prior toreaching the full contact position, the forward velocity of the ram isreduced graduatedly or continuously from a maximum forward velocity inthe first phase of the forward movement to the full contact forwardvelocity.
 26. The method of claim 25, wherein prior to reaching the fullcontact position, the forward velocity of the ram is reduced graduatedlyor continuously according to a predetermined forward velocity profile.27. The method of claim 26, wherein said step of advancing the ramduring the first phase of the forward movement includes initiallyadvancing the ram from the start position at a first forward velocity toa predetermined first position which is in front of the full contactposition but at which the pressing space is still only partially filledby the product, and further advancing the ram, at a second forwardvelocity which is lower than the first forward velocity, from the firstposition to a second position which is positioned between the fullcontact position and the press plate.
 28. The method of claim 27,wherein the first positioned is positioned so that when the ram reachesthe first position, the pressing space is filled to a predetermineddegree or the ram is at a predetermined distance away from the fullcontact position.
 29. The method of claim 27, wherein said step offurther advancing at the second forward velocity during the second phaseof the forward movement is performed until a predetermined pressure isreached in the pressing space.
 30. The method of claim 27, furthercomprising the step of conducting a preceding pressing cycle before saidstep of advancing the ram during a first phrase and determining, duringsaid preceding pressures, at least one of the forward velocity profile,the first position, an end position of the ram, and a pressure in thepressing space when the ram is in the end position.
 31. The method ofclaim 30, further comprising the step of supplying an additional amountof the product to the pressing space between an end of the precedingpressing cycle and when the ram reaches the full contact position duringsaid step of advancing the ram during a first phase.
 32. The method ofclaim 31, further comprising the step of determining the forwardvelocity profile and the first position based on the additional amountof the product supplied to the pressing space.
 33. The method of claim30, further comprising the step of supplying an amount of a wash fluidto the pressing space between an end of the preceding pressing cycle andwhen the ram reaches the full contact position during said step ofadvancing the ram during a first phase.
 34. The method of claim 33,further comprising the step of determining the forward velocity profileand the first position based on the amount of the wash fluid supplied tothe pressing space.
 35. The method of claim 24, further comprising thestep of regulating the forward velocity of the ram during the secondphase of the forward movement by implementing a predetermined pressurecurve during the pressing out of the liquid phase from the product whenthe pressure in the pressing space reaches a predetermined value or whenthe ram reaches a predetermined position.
 36. The method of claim 35,wherein the pressure curve is selected as a function of at least one ofthe product and an effective runoff of the liquid phase.
 37. The methodof claim 24, wherein the filter press further comprises a plurality offlexible filter drainage elements installed between the ram and thepress plate, said method further comprising the steps of allowing theliquid phase of the product to leave the pressing space and maintainingthe solid phase of the product in the pressing space during a pressingcycle using the filter drainage elements.
 38. The method of claim 24,wherein the product to be pressed is fruit pulp or vegetable pulp.
 39. Afilter press comprising: a press jacket; a press plate at one end of thepress jacket; and a ram in the press jacket and movable relative to thepress plate; a press control unit for controlling movement of the ramrelative to the press plate, wherein the press jacket, the press plateand the ram define a pressing space for holding a product to be pressed,and wherein the press control unit is operable to automaticallyimplement the method of claim
 24. 40. The filter press of claim 39,wherein the press control unit is configured to control the forwardmovement of the ram so that the ram moves, during a first phase of theforward movement, from the start position to a full contact positionwhich is positioned between the start position and the press plate andat which the volume of the pressing space becomes equal to the volume ofthe product, the ram exerting no pressure on the product during thefirst phase of the forward movement to press liquid phase out of theproduct; and the ram moves, during a second phase of the forwardmovement, toward the press plate from the full contact position the ramexerting pressure on the product during the second phase of the forwardmovement to press liquid phase out of the product, wherein at the fullcontact position, the ram has a full contact forward velocity which islower than an average forward velocity averaged over the first phase ofthe forward movement.
 41. The filter press of claim 39, wherein thepress control unit is configured to control the forward movement of theram in accordance with a graduated forward velocity profile or acontinuous forward velocity profile.
 42. The filter press of claim 41,wherein the graduated forward velocity profile or the continuous forwardvelocity profile is predetermined as a function of at least one of aquantity of the product in the pressing space and type of the product.43. The filter press of claim 39, wherein the press control unit isconfigured to control the forward movement of the ram so that the rammoves initially from the start position at a first forward velocity to apredetermined first position which is in front the full contact positionbut at which the pressing space is still only partially filled by theproduct, and so that the ram moves, at a second forward velocity whichis lower than the first forward velocity, from the first position to asecond position which is positioned between the full contact positionand the press plate.
 44. The filter press of claim 43, wherein the presscontrol unit is configured to determine in advance at least one of adegree to which the pressing space is filled at various positions of theram or the full contact position, the press control unit beingconfigured to adjust a forward velocity profile of the ram so that whenthe ram reaches the first position, the pressing space is filled to apredetermined degree or the ram is at a predetermined distance away fromthe full contact position.
 45. The filter press of claim 39, wherein thepress control unit is configured to control the forward movement of theram during the second phase of the forward movement so that apredetermined pressure curve in the pressing space is implemented duringthe pressing out of the liquid phase from the product.
 46. The filterpress of claim 45, wherein the pressure curve is predetermined as afunction of the product.
 47. The filter press of claim 39, wherein thepress control unit is configured to increase pressure in the pressingspace as a function of a runoff of the liquid phase.
 48. The filterpress of claim 39, wherein the press control unit is configured toautomatically control at least one of supplying the product to thepressing space and supplying of a wash liquid to the pressing space. 49.The filter press of claim 39, further comprising a plurality of flexiblefilter drainage elements installed between the ram and the press plate,the filter drainage elements allowing the liquid phase of the product toleave the pressing space while maintaining a solid phase of the productwithin the pressing space during a pressing cycle.
 50. The filter pressof claim 39, wherein the product to be pressed is fruit pulp orvegetable pulp.